Scientists unravel greenfly DNA code... now they can get to work on wiping them out

Breakthrough: Greenfly, pictured here with a ladybeetle, may have met its match

Their ability to ruin the best blooms and the juiciest buds has made them the bane of the gardener's life.

But the pesky greenfly could soon meet its match, thanks to advances in genetics.

Widespread use of conventional insecticides has led to greenfly and other aphids become resistant to almost all chemicals, in much the same way as hospital superbugs have become tolerant of antibiotics.

Last night, an international team of scientists announced they had
deciphered an aphid's genome, or entire cache of DNA for the first time.

Armed
with the genetic blueprint, they can start to look for weak spots that
can be targeted with new designer pesticides, the journal PLoS Biology
reports.

Researcher Dr Denis Tagu, of the French National
Institute for Agricultural Research, said: 'It is similar to describing
the anatomy of the human body, in the past.

'We are at the very
beginning of using it to understand how these insects function and how
they are adapted to feed from plants and provoke damage in agriculture.

One
target could be the aphid's defence against disease, which the
scientists have already established is not as robust as that of other
insects.

Researcher Nicole Gerardo, of Emory University in
Atlanta in the US, said: 'This is the first look at the genome of a
whole group of insects we knew little about.

'We went into this
expecting to find that same set of immune system genes that we've seen
in the genomes of flies, mosquitoes and bees.

'Aphids have some
components of an immune system but they are missing the genes that we
thought were critical to insect immunity.

'Given these missing genes, it seems that aphids have a weak immune system.'

Despite missing some genes, the insect studied boasts 35,000 genes in total, some 10,000 more than in the human genome.

It is thought that some of the genes are duplicates that provide a 'back-up' of its genetic material.

Another
possibility is that the extra genes are essential for their complicated
lifestyle. From birth, the female aphid contains embryos that also
contain embryos.

'She is born containing her granddaughters,' said Dr Gerardo.

The blueprint will be hugely useful in formulating chemicals against greenfly.

Other possibilities include insecticides that kill greenfly but leave bees and other 'friendly' insects unharmed.

The blueprint is the culmination of a decade of work by several hundred scientists from around the world.

They include Professor Lin Field of the Government-funded Rothamsted agricultural research institute in Hertfordshire.

She
said: 'The issue we are interested in is the way these greenfly find
their host plant. The plants give off odours which are detected by
proteins in the aphid's antennae.

'If you could block that interaction you might prevent the aphid from getting to the crop.'

The aphid sequenced is the pea aphid, one of many types of greenfly.

Professor Field said: 'We hope we can use this genome to look at genes in other aphids. It is a big step for aphid control.'